Lens grinding and polishing machine



8, 1939. w. A. LOCRHART 2,168,843

LENS GRINDING AND POLISHING MACHINE Filed Feb. 2, 1937 6 Sheets-Sheet 1 Aug. 8, 1939. w. A. LOCKHART LENS GRINDING AND POLISHING MACHINE Filed Feb. 2, 1937 6 Sheets-Sheet 2 NTUR g- 3, 1939- N w. A.ILOCKHA RT 2,168,843

LENS GRINDING AND POLISHING MACHINE Filed Feb. 2, 193'? 6 Sheets-Sheet 3 v k? E Q Q N g Q Q Q INvENTuR Q Aug. 8, 1939. w. A. LOCKHART LENS GRINDING AND POLISHING MACHINE Filed Feb 2, 1937 6 Sheets-Sheet 4 INVENT UR f Aug. 8, 1939. w. A. LOCKHART 2,168,843

' LENS QBINDING AND POLISHING MACHINE I Filed Feb. 2, 1937 s Sheets-Sheet 5 ZEZ g9 93 a/ fiaasgkgzr- '97 35 3 99 9998 Aug. "8, 1939. w. A. LOCKHART LENS GRINDING AND POLISHING MACHINE Filed Feb] 2. 1937 6 Sheets-Sheet 6 Patented Aug. 8, 1939 LENS GRINDING AND POLISHING MACHINE William A. Lockhart, Geneva, N. Y., assignor to Shuron Optical Company, Inc., Geneva, N. Y., a corporation oi New York Application February 2, 1937, Serial No. 123,642

19 Claims.

This invention relates to improvements in a grinding and polishing machine for lenses or analogous articles.

The main object of this invention is to provide a durably constructed, highly eflicient apparatus for grinding and polishing the surfaces of lenses or analogous objects and particularly, curved surfaces'such-as found'in bifocal and toric lenses having more or less complex curvatures.

In carrying out the above mentioned object, I have produced a grinding and polishing mechanism having several important and distinctive features which peculiarly adapt the mechanism for efllcaciously producing exceptionally high grade work, that is, for producing a polished surface which is not only accurate in that it corresponds exactly to the surface of the grinding lap, but is also free from distortions and waves. This desirable result I accomplish, at least in part, as follows:

First, by providing operating means whereby the grinding and polishing is effected by compounded rectilinear and circular motions imparted to the grinding and polishing couple by.

which the path of traversing movement thereof is continually changing throughout the successive strokes and cycles of operation so that a given point on the surface of the movable member, whether it is the lens or the lap or both, very seldom, if ever, travels twice in the same path.

Second, by producing a relatively high pressure between the lens and lap, and at the same time maintaining such pressure substantially constant throughout the cycles of operation irre spective of variations in the thickness of either the lens or the lap or in both the lens and lap, and also by providing means whereby the lap spindle is prevented from axial vibration during the grinding and polishing action,- particularly when the radius of curvature of the lens surface is relatively short.

-Third, by maintaining a film of abrasive or grinding material betweenthe lens and lap at all times by periodically releasing the pressure between lens and lap only sufliciently to permit justment for bringing the axis of the lens into alignment with the corresponding axis of the lap when alens is remounted in the machine as for polishing. 4

In addition to the above, it is an object of this invention to provide the machine with a time control mechanism which may be selectively set to automatically goverrr the period of operation 'of the machine, depending upon the condition and degree of curvature of the surface to be treated, the amount of abrasive material used, etc., whereby an operator may have charge of several operating m cs at the same time.

Another object of t e invention resides in providing an adjustable means for varying the degree of movement of the motions of operation of the other whereby the machine may be operated at a relatively high speed when grinding or polishing relatively weak lenses, that is, lenses up to ten diopter, and to operate the machine at a slower rate of speed when grinding or polishing relatively strong lenses, that is, all lenses of ten diopter or more. Furthermore, the speed of operation may be controlled whereby the reciprocal movements for the cylinder and base curves may be controlled independently of each other when one of said curves is of relatively long radius, and the other curve is of relatively short radius. v

A still further object of the invention is to provide the-machine with a compensator which, when the machine is used for grinding or polishing lenses or surfaces of complex curvatures, me-

, chanically and automatically assists in reversing the direction of movement of the movable elements of the couple at the end of each reciprocal movement.

Other objects and advantages pertaining to the structure of the apparatus and to the form and relation of the parts thereof will more fully appear from the following description taken in connection with the accompa-nying drawings in which:

Figure 1 is a perspective view of an apparatus embodying the various features of this invention. Figure 2 is an enlarged detail transverse sectional view taken substantially in the plane of the line 22, Figure 1.

Figure 3 is a detail vertical sectional view through a portion of the automatic time control mechanism taken substantially in the plane of the line 3-4, Figure 1.

Figure 4 is a longitudinal vertical sectional view taken substantially in the plane of the line (-4, Figures 1 and 6.

Figure 5 is a horizontal sectional view taken on line 5-5, Figure 4.

Figure 6 is a transverse vertical sectional view taken online 6-6, Figure 5 with the lower portion of the housing broken away.

Figure 7 is a detail horizontal sectional view taken on line 1-1, Figure 6 Figure 8 is a detail vertical sectional view taken on line 8-3, Figure 6.

Figure 9 is a detail horizontal sectional view taken on line 3-9, Figure 6.

i ure 10 is a detail side elevation, partly in section, taken substantially in the plane of the'line i3l3, Figure '6.

Figure 11 is a sectional view taken on line "-1 I, Figure 4.

Figure 12 is a sectional view taken on line i2-i2, Figure 6.

Figure 13 is a detail sectional view taken substantially on line 13-13, Figure 5.

Figure 14 is a vertical sectional view through the lens block and the supporting yoke therefor, together with the upper portion of the lap taken on line l4--l 4, Figure 5 and illustrating a plus or convex lens between the block and lap.

Figure 15 is a view similar to Figure 14 illustrating the lap and-block with a minus or concave lens mounted in operative relation therewith.

Figure 16 is. a detail horizontal sectional view taken on line iil3, Figure 4.

Figure 17 is a diagrammatic view illustrating the lens holder during a movement thereof through the base stroke together with the action of the compensator thereupon.

Figure 18 is a diagrammatic view illustrating the path of 'the center of the lens during the movement thereof through the cycles of reciprocal movements.

Figure 19 is a similar view illustrating a portion of the path of the center of the lens produced by the combination of the reciprocal motions with the circular motion.

The apparatus as illustrated in the drawings comprises a main supporting'frame or housing I having a cover 2 removably secured to the upper side thereof. The lower forward portion of the housing -I is forwardly projected as at 3 and this projection is provided with a bottom 4 and side walls 3 which form a tray adapted to catch the waste abrasive. To the upper portion of the opposite or rear end of the housing I is secured a gear case 1 by means of screws 3 or the like, as shown in Figure 4. The gear case is provided with a normally closed bottom wall 3 to enable it to retain a quantity of oil for lubrication purposes, while the upper side of the case is closed.

by a cover ill removably'secured thereto. The inner side wall of gear case 1 is provided with bearing supports 12 and'l2' which project outhorizontally disposed drive shafts ll, 15 and l3,

which, as shown in Figures 4, 5 and 8 extend transversely through the case and are arranged in parallel spaced relation to each other longitudinally of said case. These, drive shafts may be journaled in any suitable manner in the side walls of gear case 9 and each shaft extends rearwardly beyond the rear side wall of the case and has operatively connected'therewith one or more respective pulleys l1, l3 and I9. Each of the pulleys l1, l3 and i3 is connected by a respective belt 20 with a corresponding drive pulley 21, 22 and 23 secured to the outer end of a driven shaft 24 which is rotatably mounted, as shown in Fig-' ure 4, in a horizontal plane beneath the gear case 9 in a supporting bracket 25 secured to the rear end wall of the housing I. Secured to the driven shaft 24 is a gear 26 which has meshing engagement with a gear 23' secured to one end of a drive shaft 21 which is also journaled in the bracket 25 to extend substantially normal to the shaft 24. Mounted on the outer end of shaft 21 are pulleys 23 and 29, one of said pulleys as 23, being secured to the shaft inany suitable manner to form a drive pulley, while'the other one is an idle pulley rotatably mounted on said shaft.

Mounted in the gear case 3 are also a plurality of, in this instance three, counter shafts 33, 3| and 32 which are journaled in the side walls of the case to extend in a horizontal plane beneath the drive shafts 14, I5 and 16 respectively, as shown in Figures 4, 5 and 8. The drive shafts 14, I5 and ii are each operatively connected with a coupling or gear member 34 mounted upon each drive shaft within the gear case. Each of these coupling members has the ends thereof provided with a set of gear teeth 35 and 36 of different pitch diameters and which are adapted to mesh with gear members 31 and 33 respectively which also differ in size one from the other and are fixedly secured to the corresponding counter shaft. As shown each set of gear teeth 35 and gears 31 are of the same pitch diameter while the pitch diameter of gear teeth 36 is smaller than that of gears 33. It therefore follows that when gear teeth 35 mesh with a gear 31 the corresponding shafts will rotate at the same speed and when teeth 33 mesh with a gear 33 the corresponding counter shaft will be rotated at a slower speed than that of the drive shaft.

The coupling members 34 are each slidably mounted upon their respective shafts and are splined thereto so as to be rotated thereby. Each coupling member is moved axially along the shaft by a forked arm 39 adapted to ride in a peripheral groove 33' formed in each coupling 34. Each arm 39 extends upwardly above the corresponding driveshaft to a position adjacent the inner face of the-cover l3 and has secured thereto a control member or button having a screw 40 which extends downwardly through an elongated slot 13' formed in said cover transversely thereof into screw threaded engagement with the corresponding arm 33 as shown in Figures 4 and 8. A washer 41 may, as shown, be inserted between each control button 40 and the cover III for closing the slot 13', and which co-acts with the button and screw for clamping the arm to the cover whereby the corresponding coupling 33 may be releasably secured-in the adjusted position for selectively maintaining the gear members and 36 in meshing engagement with the corresponding gear members 31 and 33.

It will now be observed that each drive shaft l4, l3 and I3 and the corresponding counter shaft 33, 31 and 32 together with the gear connection therebetween constitute a variable speed power transmission mechanism Each of ,these mechanisms i s utilized toproduce one of the compounded rectilinear and circular motionsimparted to 1 the movable elements of the grinding an clfpolishing couple in the following manner; H

Lens holder operating means Three substantially rectangular frame, carriers 43, 44 and 45 arehorizontally disposedwithin'the housing l 'as shown in'Figures 4, 5,' 6 and 16, in cooperative relationwith each other.' 43 is a base carrier for producing reciprocal movement of the movable, elements of the grinding couple along the base curve or longitudinally of the lens; 44 is a'c'ylinder carrier for moving vsaid elements along the cylinder cu'rvefor transversely of the lens; and 45 is a spindle carrier which supports a spindle 46 for actuating a lens holder and which is adapted to transmit the circular motion to saidholder. The base carrier or frame-43 is reciprocally mountedupon a plurality of, in this instance four; studs 41, secured as shown in Figure 16, to the side walls of housing I. The cylinder carrier frame is mounted within the base frame 43 and is supported as shown in Figure 16,

- by said base frame for reciprocative movement relative thereto by four, studs 48 secured to the end portions of the frame 44 to extend outwardly therefrom at substantially right angles to the studs 4] and have the outer ends thereof slidably supported in suitable bearing members pro-' vided in the ends of base frame 43.

The base frame 43'is operatively connected with one of the-counter shafts as 32 by means of a pitman rod 50 which isvpivotally connected at one end to, a side of frame .43 intermediate the .ends thereof .by a pin 5|. The pitman rod extends in a substantiallyhorizontal plane across the frame 43 and has the other end thereof journalcd upon a drive pin 52 secured to or made integral' with a drive block'53 which is slidably mounted in a diametrically disposed slot 54' provided in anvenlarged head '54secured to or made integral with .a vertically'disposed shaft 55. This shaft 55 is journaled in a bearing support 56 secured to the adjacent side wall of housing I, as shown in Figure 6, which has the upper end thereof arranged-in spaced'relation to cover 2. Mounted upon shaft V55=adjacent the upperend of bearing support 56 is a gear member 51 which has meshing engagement with a similar gear member 58 secured to the inner end of counter shaft 32 and by which shaft55 is rotated.

The hub 51' of gear 51, as shown in Figure 6, extends'upwardly through an aperture provided in the cover land has secured to the outerend thereof a flanged dialv 59. Shaft 55, inthis instance, is a tubular member and has journaled therein a spindle 60 which extends abovethe -dial- 59 and hassecuredto-the upper end thereof a pointer 6| which is adapted to register in any one of a plurality-pf recesses .62 provided in-the flange of said dial,;as 'shownin Figures land 6. The lower end of spindle 60 is providedwith a pendant boss oripin-63 arranged eccentrically relative to the spindle liiland which extends into an elongated slot 64 in the block 53 arranged trans- .versely thereof substantially normal to recess 54 in head 54, as shown in Figure 12 The spindle 60 is also adapted to rnove vertically relative to shaft 55 andthis vertical movement of the spindle I is limited .by means of a stop screw 65 secured to move longitudinally through said slot.

of greater'axial widththan the diameter of the adl'acentend of the screw. v i v It will now be observedthat the degree of travel of-pitman 50 andframe 43 maybe controlled during, the operation of the machineby lifting spindle 68 sufliciently to bring the pointer 6| out of registration with one of the dialrecesses B2 and then rotating said spindle to bring connected with the counter shaft 3| and for this purpose is provided with an extension 68 which projects from the rear end thereof over the adjacent end of frame 43; see Figure 4. The upper surface of extension 68 is provided with a transversely disposed slot 69, as shown in Figure 11, in which is mounted a bearing member 10 adapted In the bearing member Ill is journaled a driven pin II which is connected with the lower side of a drive block 12, mounted for rociprocated movement in a diametrically disposed recess 13 provided in a head 14 secured to or made inte l W th a. V rtically disposed shaft 15 which is journaled in the hereinbefore mentioned bearing support l2 connected with the gear case 1. The shaft 15 extends' upwardly beyond the support l2 and has secured thereto a gear member 16 which is in meshing engagement with a similar gear 11 secured tothe inner end of shaft 3i, as shown 1n Figure 4, to be rotated thereby.

l I i The gear 16 has the hub 16' thereof extended like the hub of gear 51 upwardly through an opening provided in cover 2 and has secured to the upper end thereof a flanged dial 11 adapted to rotate with said gear. Shaft 15 is a tubular member and has journaled therein a spindle 19 which extends above the dial 11 and has secured thereto a pointer 80 adapted to register in any one of a plurality of recesses 8| formed in the flange of said dial, as shown in Figures 1 and 4. The lower end of spindle'l9 is provided with a pendant pinor boss 83 which is arranged eccentrically therewith, as shown in Figure 11. The boss 83 extends into an elongated slot 84 provided in the upper face of the drive block 12 and which eX-.

tends substantially normal to slot 69. Spindle I9 is maintained against excessive vertical movement by means of a stop screw 85 secured in the hub 16' of gear 16 and the adjacent portion of shaft 15 as shown in Figure 4, and which extends into a peripheral groove or recess 86 PTO? vided in spindle 19. The relation of the inner end of the stop screw 85 and the width of the recess 86 are such that the pointer 80 may be lifted out of registration with arecess 8| by vertical movement of spindle 19 without completely disengaging the boss 83 with the drive head 12. One reason for providing means for varying the stroke of the base and cylinder frames is to enable the machine to efficaciously grind surfaces which vary from a substantially flat surface to curved surfaces having relatively short radii, the flat surfaces requiring the longer stroke.

The spindle carrier or frame 45 is operatively connected with the cylinder frame 44 to be reciprocated thereby and at the same is operatively connected with the counter shaft 30 mounted in gear case 9 to be actuated by said shaft with a circular motion in the following manner:

Two stub shafts 88 are journaled in vertical position, one at either end of frame, in axially spaced bearing members 89 secured to said frame. The lower end of each shaft 88 extends a short distance below the frame 44 and has secured thereto a gear 90 which is in meshing engagement with a similar gear RI. The gears III are secured to a horizontally disposed shaft 92 journaled in a support 93 secured to the underside of the frame 44, as shown in Figure 4. Secured to the shaft 92, as shown in Figures 4 and 9, is a spur gear 95 which is in meshing engagement with a spur gear 96 secured to one end of a stub shaft 91 which is journaled in the support 93 in parallel relation with shaft 92; see Figure 9. The other end of shaft 91' is connected by a universal joint 88 with one end of a shaft 99 which has the other end thereof connected by a similar universal joint 98 with a stub shaft I00 journaled in the rear end wall of housing I in a horizontal plane beneath the gear case 8 and in a vertical plane extending intermediate the counter shafts 30 and 3|. To the shaft Hill is secured a sprocket wheel IOI which is connected by a sprocket chain I02 with a second sprocket wheel I03 secured to theinner end of counter shaft 30, as shown in Figure 8.

Shaft 99 is a sectional member, one section of which, as 99', has a tubular end portion which slidably receives an end portion of the second section as Ell-l" therein, said sections being secured together to cause the same to rotate in unison by a pin and slot connection I04. It will be observed that the purpose of the shaft 99 being formed in section and the connection thereof with shafts 97 and I00 by universal joints is to permit the free reciprocative movements of shaft 91 with frames 43 and 44.

The upper ends of the shafts 88 terminate substantially flush with the upper face of the adjacent portion of the frame 44 and each shaft 88 is provided with an upwardly extending boss or pin I05 arranged eccentrically therewith. Mounted on each pin I05 is a sleeve I06 which, in turn, is mounted in a bearing member I01 mounted in the lower side of the spindle frame 45; see Figures 4 and 6. The bearings I01 are spaced apart a distance substantially equal to the distance between the axes of shafts 88 so that during rotation of said shafts, a circular motion corresponding to the degree pins I05 are offset from the axes of shafts 88 will be transmitted to the spindle frame through the medium of pins I05 and bearings I01 relative to the cylinder frame 44.

The spindle frame 45 is provided with a pair of upwardly projecting arms I09 and H0 arranged one adjacent the rear and forward ends thereof respectively. The upper ends of the arms I09 and H0 are each provided with a bearing member'III which rotatably supports the hereinbefore mentioned spindle 46. The spindle 46 is fixedly secured to one of the bearings I II by a nut 46; see Figure 5. whereby the spindle will reciprocate in unison with said bearing and with the frame 45. The forward arm IIO projects forwardly from the frame 45 in close aligned relation with an opening II2 provided in the forward end of housing I. This opening is somewhat larger in diameter than the upper end portion of arm. NO to permit free lateral movement of said arm therein. A flexible diaphragm H3 composed of leather, rubber or the like, is secured to the housing I to extend across the opening H2 adjacent the outer face of the upper end of arm H0 for tightly closing said opening to prevent dust or abrasive entering the housing or oil splashing out. The diaphragm has a central opening II 3' through which the outer end portion of the spindle 46 extends. said opening being of substantially the same diameter as the spindle so that the diaphragm will closely engage said spindle. To the outer end of spindle 46 is secured a U-shaped support or yoke II4 which has the arms II 4' thereof extending for wardly from the spindle in substantially thehorizontal plane of the spindle.

Lens holder To the outer end of each arm 4' is secured a pivotal screw II5; see Figure 2. These pivotal screws extend inwardly from the arms H4 in substantially coaxial alignment with each other and rotatably engage a respective arm H6 of a lens holder Ill-which also includes a cross bar H8 and a lens supporting block II9. Each of these arms H6 extends upwardly from the corresponding screw II5 and is provided with a recess H8 which extends longitudinally thereof from near the upper end of the arm toward the pivotal screw for adjustably receiving therein the corresponding end of cross bar II8. Each end portion of the cross bar I I8 is provided with a key member H8 positioned in the slot H6, see

Figure 2, to maintain said bar and member against relative rotation. A threaded cylindrical portion extends from the key H8 and a flanged nut I20 is screw threaded thereon which co-acts with a corresponding shoulder II8" adjacent the key member for adjustably clamping the arm Hi to the cross bar. Each arm H6 has one vertical side thereof provided with spaced index lines I2I adapted to align with a guide line I22 formed on the shoulder H8" and adjacent portion of the cross bar, as shown in Figure 2, whereby the cross bar may be readily arranged in predetermined spaced relation to the pivotal screws IIS for maintaining differently formed lenses in predetermined relation with the axis of pivotal screws H5 and of spindle 46 for a purpose which will hereinafter more fully appear.

The lens supporting block IIS, as shown, is circular in plan view and is provided with a diametrically disposed rib H9. The cross bar H8 is provided with a pair of clamping plates I24 and I25 which are L-shaped in longitudinal cross section, as shown in Figure 4. One of the clamping plates as I24 is fixedly secured by any suitable means to the rear side of the cross bar H8 substantially midway between the ends thereof. The other clamping plate I25 is removably secured to the cross bar by a thumb screw I25. The ends of the clamping plates opposite the transversely disposed flange thereof which as shown engage the upper edge of the cross bar H8, extend a short distance below the cross bar for receiving the lens block rib H9 therebetween. These lower portions of the plates preferably have the inner adjacent surfaces thereof serrated for gripping the longitudinal sides of the rib so that the lens block may thereby be releasably secured to the cross bar H8. The degree of rocking movement of arms H6 and, therefore, cross bar H8, about screws H5 is limited by a stop pin I21 secured to the lower end. of each arm and which extends outwardly therefrom between a pair of spaced limiting pins or shoulders I21 secured tothe outer ends of arms 4' of the yoke II4, as shown in Figures 2 and 4 whereby the lens holder is maintained in a more or less vertical position when inoperative.

Lap supporting means A grinding lap I28 adapted to cooperate with the lens block 9 for grinding surfaces is releasably mounted upon the upper end of a supporting spindle I29 which extends vertically through a bearing member I30 mounted in a bearing support I3I secured to the bottom 4 of the housing projection 3.- The bearing support I3I, in this instance, is a cylindrical member which extends upwardly some distance beyond the bottom wall 4 and has the lower end thereof ex tending through a suitable aperture provided in said wall. The bearing member I30 comprises a cylindrical ball race I32 composed of tempered steel or the like, of greater interior diameter than the diameter of spindle I29. This ball race extends axially through the bearing support I3I and is secured therein by nuts I33 screw threaded one in either end of. the bearing support. Within the ball race I32 is rotatably mounted a cylindrical retaining member I34. This ball retaining member is adapted to easily fit between the spindle I29 and the ball race I32 and is provided with a multiplicity of apertures, each of which receives therein a respective bearing ball I35 adapted to have a free rolling engagement with the inner wall of the ball race and with the spindle I29. It is, therefore, seen that the spindle I29 is supported for a considerable portion of the axial length thereof by the bearing member I30, whereby said spindle may move vertically with a minimum amount of friction. This feature is very essential in order that the spindle may be easily held steady against axial vibration or chattering during the grinding operation. In order that laps of different sizes and formations may be readily secured to the spindle I29, the upper end of the spindle is provided with a head I31 whichis adapted to be removably connected therewith. Adjacent opposite sides of the head I31 are positioned'clamping plates I35 and I39 which are connected with the head for movement toward and from each other by a clamping screw I40 extending through aligned openings. provided in the plates and head and a finger nut I4I screw threaded on the clampin'g screw, as shown in Figure 4. The upper end portions of the clamping plates I35 and I39 extend a short distance above the head I31 and then-inwardlyover the head into frictional engagement with the lap I25. The head I31 is maintained against rotation relative to spindle I29 by a pin I43secured in the upper end of the spindle and which extends outwardly from one side thereof into a The spindle I29 is slot I31" formed in the lower portion of the-support I31.

shoulder I29 arranged a short distance below the 'head'I31 and an inverted cup-shaped cap I44 is mounted-on the upper end of the spindle in engagement with the shoulder I29. This cap extends downwardly over the bearing support I3I and contacts with an outwardly extending mar'- ginal flange I3I' formed on the upper end of said support, as shown in Figure 2, for preventing dust and-grinding materials from passing to the interior thereof and to the bearing member I35.-

provided with a peripheral Pressure means The lower end of the spindle I29 extends below the bottom wall 4 into the lower portion of the base projection 3 and contacts with one end of an arm I45 which extends rearwardly from the spindle. The other end of arm I45 is clamped or otherwise secured to the inner end of a sleeve I 46, as shown in Figures 4 and 6. Sleeve I46 extends transversely of the housing I and is journaled in one side wall thereof some distance at the rear of the spindle I29. A shaft I41 is journaled in the sleeve I46 and has one end thereof rotatably mounted in the opposite side wall of housing I to that in which sleeve-I46 is journaled, as shown in Figure 6. Thesleeve I46 extends from a position substantially midway between the side walls of the housing to a position a relatively short distance beyond one of said walls. Sleeve I46 is. maintained against e outward axial movement by a fiange I46 connected therewith and which engages the inner side of the wall of the housing in which the 6.. This collar I49 is secured to the shaft I41 to rotatetherewith and has one end of a relatively heavy, stiff spring I50 connected therewith. This spring is coiled about the sleeve I48 and has the other end thereof extended forwardly from the sleeve into engagement with arm I45 a short distance from the outer end thereof as shown in Figure 4 for yieldingly urging the arm upwardly when shaft I41 is rotated.

Rotation of shaft I41 is produced by a lever I52 secured at one end to the outer end of the shaft. This lever extends, as shown in Figure 10, forwardly from shaft I41 adjacent the outer face of housing I to the forward end thereof which is bent-downwardly to form a hand grip l53. The underside of said lever is provided with a recess I52 which extends inwardly from the grip I53 'to a position intermediate the ends of the arm where said arm is oflset as 'at I54, Figure 5, to form a recess I54 at the inner side of the lever in align; ment with the recess I52. In the recess I52 is positioned a rod detent I55 which is mounted for longitudinal reciprocative movement, as shown in Figure 10, with one end thereof positioned in an aperture provided in the hand grip- I53. while the other end of the rod detent extends into' the recess I54. Upon the rod I55 is secured a finger piece or trigger I55 whichisnormally positioned a short distance inwardly from the hand grip I53 and a spring I-51 mounted on the rod between the finger piece and hand grip normally urges the rod inwardly, said inward movement of rod being limited by the engagement of the finger piece I55 with one of a pair of guide pins I55 which extend transversely of the recess. I52 fortmaintalning the rod I55 in said recess.

A ratchet lever I55 is rotatably mounted interadapted to be engaged by the rod detent I55. The

other-"arm I55" of the lever I50 extends rearwardly from the shaft I41 into engagement with the lower end of a vertically disposed push rod I62. This rod extends upwardly through the adjacent sidewall of housing I which extends outwardly over the lower portion of the housing, as shown in Figures 6 and 10 and through an upwardly extending guide-boss I63 secured to or made integral with said wall at the inner side thereof. The upper end of the push rod has secured thereto a head I64 which is adapted to be engaged by a cam I65 secured to a shaft I66 which extends transversely of the housing I and has the ends thereof journaled in opposite side walls of said housing. The cam I65 is adapted to intermittently force the push rod I62 downwardly during rotation of the shaft I66 for effecting rocking movement of the ratchet lever I60 and the lever I52 connected therewith by the rod detent I55.

Secured to the outer end of the sleeve I46 intermediate the lever m and the adjacent side wall of the housing I, is a sector-like dial member I68 which extends forwardly from the sleeve I46 and has the outer end I69 thereof arranged in a vertical plane concentric with the sleeve, see Figure 10. The outer peripheral face of end I69 is provided with indicia in the form of index lines I10 spaced to represent pounds pressure or fractions thereof exerted by spring I 50 through arm I45 upon spindle I29. These lines I10 are arranged to align with a lateral projection I" provided on the inner face of the lever I 52 adjacent the end I69 as shown in Figure 5.

The lower portion of the outer end of the dial member I66 is provided with a laterally projecting lug I12 which extends beneath the lever I52 for limiting the swinging movement of the lever downwardly relative to said member.

It will now be observed that the vertical movement of spindle I29 for bringing the lap I28 into and out of cooperative relation with a piece of work, as lens L, Figures 14 and 15, secured to the lens block II9, may be controlled by the manipulation of the lever I52, in the following manner. When the lever I52 and arm I45 are in their lowermost position, as shown inFlgures 4 and 10, the upward movement of lever I52 will effect rotation of shaft I41 in a corresponding direction. This rotation of shaft I41 will be transmitted by collar I49 and spring I50 to arm I45. The upward swinging movement of arm I45 thus produced, prior to the engagement of the lap I28 with the work L, will effect a corresponding rotation of sleeve I46 and also of the dial I66. Inasmuch as the resistance to the upward movement of the arm I 45 produced by the spindle I29 is insumcient to tension spring I50. the dial I66 and lever I52, together with arm I45 will rotate in unison until the lap I28 engages the work L which prevents further upward movement of spindle I29.

The continued upward movement of lever I52 after the spindle I29 is thus held by the work will place spring I50 under tension due to the rotation of shaft I41 and collar I49 produced thereby, and to the arm I45 being maintained against further upward swinging movement by the spindle I29. It will now be obvious that during the movement of the lap into operative engagement with the work there will be no appreciable tensioning of spring I50 produced. However, as soon as the lap engages the work, continued upward movement ,of lever I52 will tension spring l50 and the degree of said tension pointer "I on the lever with indicia I10 on the dial I68. During the upward rotation of lever I52 the rod detent I55 is of course maintained out of contact with the ratchet teeth I6I by the operator moving the rod outwardly against the action of spring I51. upward rotation of lever I52, the ratchet lever I will remain stationary with the arm I60" thereof maintained in contact with the push rod I62 due to the preponderance of weight being in arm I60 which also maintains the head I64 of the push rod in contact with cam I65. When the lap I26 is brought into engagement with the work L under the desired pressure produced by the tensioning of spring I50, this pressure may be maintained by the. engagement of the rod detent with the ratchet teeth I6I of the ratchet lever I60 due to the cam I65 contacting push rod I62.

It will also be understood that when the lap is thus maintained in pressure engagement with tge' work, rotation of cam I65 from the position a own in Figure 10 will intermittently permit the upward movement-of push rod I62 which releases the arm I'60" of the ratchet lever I60 and permits the other arm I60 thereof together with the lever I52 connected therewith to swing downwardly a corresponding distance. This downward movement of lever I52 will obviously rotate shaft I 41 in a direction to decrease the tension of spring I50 and thereby reduce the pressure between the grinding lap I28 and the lens L. This reduction in pressure is sufficient to permit the grinding abrasive which is forced. from between the grinding lap and lens by the high pressure produced therebetween to again enter between the contacting surfaces of the lap and Furthermore, during this circular motions relative to the lap. It is to be understood, however, that the action of cam I65 upon lever I52 is insuflicient to permit the lap to move out-of contact with the lenses is the case in some'lens grinding machine structures, and thereby prevent the forming of waves or the distortion of the lens surface which would result when using the high pressure obtained in this mechanism if the lap and lens were caused to intermittently separate during the grinding operation.

As hereinbefore stated, the lens holder H1 is maintained ina more or less inclined vertical position when the lap I28 is in the lowermost inoperative position by the co-action of the stop pins I21 and I21, as illustrated in Figure 4.

As the lap is moved upwardly toward the lens holder, the engagement of the lap with the lens causes the holder to swing about the screws 5 as an axis and thereby automatically brings the surface of the lens into cooperative relation with that portion of the surface of the lap'engaged thereby whether a flat, concave or convex lens is mounted on the lens holder.

In as muchas spring I50 is a relatively strong member, the lens L will be maintained in engagement with the grinding lap under a relatively high pressure and thus obtain maximum speed of operation; It follows, therefore, that the resistance to the travel of the lens over the surface of the lap will be proportionally greater than when using a lesser degree of pressure as in the conventionally constructed grinding machines of this class. This is particularly the case when grinding or polishing a curved surface having short radii whether such surface is convex or concave due to the necessity of forcing the lens thereof during each forward and backward stroke of the lens holder as will be apparent by referring to Figures 14 and 15.

In the lens holder II1 hereinbefore described, it will be noted. that said holder rocks about the axis of the spindle 46 as the lens is moved along the longitudinal or base axis of the lap. It will also be noted that inasmuch as the cross bar 8 of the lens holder is adjustable longitudinally of the arms Hi, the lens may be positioned with the surface thereof to be ground either above or below the axis of rotation of the spindle, that is, at the same side of said axis as the bar I It 'or at the opposite side thereof depending upon whether a convex or concave lens is to be ground. This arrangementof the lens and work holder provides for the lens to be moved by a minimum amount of power over the upwardly inclined portions of the lap surface and without producing excessive lateral thrusts of the lens upon such surfaces and the resultant excessive wear thereto which would alter the contour of thelap and result in a defective lens. The operation of the lens holder to accomplish this result is as follows:

Consider first that a plus or convex lens, as illustrated in Figures 2 and 4, is to be ground. The lens L is positioned, as shown, with the surface thereof to be ground above'the axis of rtation of spindle 4 6 and of the pivotal screws IIS by clamping the cross bar II! to the arms-Hi with the upper or outer positioned index line III in alignment with the guide line I22 on the cross bar.

It will now be apparent, by referring to Figure 14, that inasmuch as the longitudinal thrust of the spindle 46 upon the lens holder is applied at the pivotal screws Ili below the connection of the lens both with the lens holder bar III and with the lap I28, the frictional resistance to the movement of the lens over the lap will tend to rotate the holder in the opposite direction to that of the movement of. the spindle 46. The forward edge of the lens will therefore, be rocked upwardly thereby and caused to move along the upwardly inclined edge portion of the lap surface coincident therewith and without producing excessive friction between the lap and lens. If, on the other hand, a minus or concave lens is to be ground, the cross bar I ll of the lens holder is secured to the lower portion of the arms IIG, that is, with the lower index line I2I in alignment with theguide li-ne I22. When so positioned, the lens surface to be ground will be positioned below the axis of the screws IIS and of the spindle 46 and at the opposite side of the spindle axis to that'of bar Ill, as shown in Figure 15. In this arrangement of the parts, the thrust of the spindle 46 during the axial movement thereof upon the lens holder will be applied thereto above the surface of the lens engaging the lap I28, that is, at the same side of said surface as the connection of the lens with the lens holder bar II8. a

It, therefore, follows that-the force produced bylthe lateral thrust of. the lens upon the upwardly inclined central portion of said lap will be," applied to the lens holder at the opposite side of the axis of spindle 46 to that of "the lap engaging surface of the lens:' This will tend td rock the lens holder in a direction opposite to the direction of movement of the spindle l8 and thereby tend to rock the forward edge of the lens upwardlyso that'the lens will move over said surface of the lap in substantially coincidental contact therewith and thereforewith a minimum amount of lateral thrust thereupon.

When a lens with a substantially flat surface is to be ground, such surface is maintained substantially in the plane of the axis of rotation of spindle 46 by clamping the cross bar H8 to the side arms IIS with thecentral index line I2I in alignment with the guide line I22. When the parts of the lens holder are in this position, the line of thrust of thespindle 46 during the axial movement thereof upon the lens holder is sub-' stantially coincident to the lines of thrust of the lens upon the grinding lap so that the tendency of the lens holder to be rotated about the axis of the screws is reduced to a minimum and the surface of the lens will be maintained in substantially coincidental contact with the curved grinding surface of the lap.

The term coincidental contact is used in the spec fication and claims to designate that relation between the lens and lap whereby all portions of the surface of the lens being ground will engage insofar as possible the grinding surface of the lap and with a substantially uniform pressure throughout the area thereof in counter distinction to any inequality in the engagement of such surfaces that would occur if they were caused to assume a' more or less angular relation therebetween.

The hereinbefore mentioned shaft I66 for operating cam I65 is driven by the drive shaft I6 mounted in the gear case 1 through the medium of a worm gear I13 secured to the inner end of said drive shaft which, is extended beyond the bearing support I2 and a gear I14 secured to shaft I66 as shown in Figures 4 and 5.

As illustrated in Figures 5 and 8, the drive shaft It for producing the rotary movement of spindle frame 45 is provided with means for automatically reversing the direction of rotation thereof at prerotated in reverse directions by crossing one of the belts 20 therefor. These pulleys are arranged in s ightly axially spaced relation: and are selectively connected with the shaft II to produce rotation of the shaft by a clutch mechanism. This clutch mechanism comprises, in this instance, a clutch control rod I16 mounted for longitudinal reciprocative movement in the interior of shaft I which, as shown in Figures 5 and-8, is a tubular member. The outer end of the rod I16 is provided with a clutch pin I11 which extends outwardly radially therefrom through an elongated 'slot I4 provided in the adjacent portion of shaft It at one side thereof. into the path of a pair of clutch pins I18, each of which is secured to a respective driven pulley I1. The pins I18 are adaptedto project from the respective pulley inwardly toward each other and have the inner ends thereof spaced from each other a distance to readily receive the clutch pin I11 therebetweenso that when said latter pin is positioned in a, plane intermediate the pins I18 the pulleys I1 may freely rotate on shaft I4 without transmitting motion to said shaft.

The control rod I16 is moved longitudinally 7o relative to the shaft I! to bring the-pin I'" into and out of cooperative relation with the pins I18 by means of a cam I secured to the hereinbefore mentioned cam shaft I66. As shown in Figures 5, 6 and 8, a cam arm III is pivotally connected with the housing I above the shaft I66 by a pin I82 and per minute when the teeth 35 a link I83. The link I83 is pivotally connected at one end by a pin I84 to the arm I8I and rotatably connected at the other end to the inner end of rod I15 by a screw and slot connection I85 whereby said rod may rotate with the; shaft I4 relative to the link I83. The cam arm 'I 8i has the lower end portion thereof provided with an aperture I85 which receives the shaft I65 and cam I80 therein. The opposite sides of the opening I86 are curved inwardly as illustrated in Figure 8 to form a pair of diametrically opposed cam surfaces'i81 spaced apart a distance substantially equal to the longer diameter of the cam I80 and which are adapted to be alternately engaged by said cam during the rotation thereof for oscillating the arm I8I to effect axial movement of the control rod I18. A spring detent I88 connected with the housing I by a stud I89 and support block I90, as shown in Figures 5, 6 and 8, is adapted to frietionally engage a V-shaped tooth ISI formed on the lower end of the arm IOI for releasably maintaining said arm and control rod I15 in their extreme positions of movement as produced by cam I80. It will now be readily understood that the operation of the mechanism thus far described is as follows:

Inasmuch as the pulle'ys I9 and 23, as shown in Figures 4 and 5 for driving the power transmission mechanism for operating the base frame 43 are of different relative diameters than the pulleys 22 and I8 for operating the power transmission mechanism which actuates the cylinder frame 44, these frames will be operated at different speeds. For convenience let it be assumed that the speed of operation of the drive shaft I6 is one hundred forty R. P. M. so that the base frame 43 actuated thereby will operate at two hundred eighty strokes per minute when the teeth 35 of the couple 34 on shaft iii are in engagement with the gear 31 associated therewith. Let it also be assumed that the speed of operation of the drive shaft I5 is one hundred thirty R. P. M. so that the cylinder frame 44 will be operated at two hundred sixty strokes of the couple 34 mounted on the shaft I5 are in engagement with the gear 31 associated therewith.

In addition to the above, it will be observed by referring to Figures 11 and 12 that the maximum degree of throw of the drive block 53 for the base frame is greater than the throw of the drive block 12 for the cylinder frame so that the rectilinear movement of the base f1 ame 43 and, therefore, the movement of the lens longitudinally of the lap I28 will be greater than the rectilinear movement of the cylinder frame 44 and, therefore, of the movement of the lens transversely of said lap.

This ratio of the longitudinal movement or throw to that of the transverse motion or throw of the base and cylinder frames in the structure illustrated is as 2 /2 to 1. By referring to Figures 4 and 5, it will be noted that the drive pulleys II and the driven pulleys I1 which operate the power transmission mechanism connected with the spindie frame 45 are of substantially the same diameter so that the speed of operation of the drive shaft I4 is intermediate that of the speed of rotation of the shafts I5 and IE or approximately one hundred thirty five R. P. M. It will thus be seen that when the teeth 35 of the couple 84 mounted on shaft I4 are in engagement with the gear 81, the rotary movement of the frame 45 will equal that of shaft I4.

Assuming now that a lens L is secured to the lens block IIS and that the lap I28 has been moved into pressure engagement with the lens, that each coupling element 84 has been moved by the manipulation of the control buttons 40 to bring the teeth 34 thereof into engagement with respective gears 81 and that the drive blocks 53 and 12 for the base and cylinder frames have been set for maximum throw through the medium of respective pointers 8| and 80.

Now as the drive shaft 21 is rotated by any suitable means as by a belt I93 mounted on drive pulley 28 and connected with any-suitable source of power, it is obvious that the spindle 45 and lens L connected therewith will have a curvilinear movement across the grinding surface of the lap I 20 compounded of two crank-produced rectilinear movements at right angles to each other and one circular movement.

Inasmuch as the stroke of the base frame 43 is substantially two and one-half times the stroke of the cylinder frame 44, if the base frame be operated at two hundred eighty strokes per minute and the cylinder frame correspondingly operated at two hundred sixty strokes per minute, the general path of movement of the lens over the face of the grinding lap produced by the two rectilinear movements only would be substantially as represented in Figure 18, while the actual path of the lens over the surface of the lap produced by the combined actions of the base and cylinder frames with the spindle frame 45 will be substantially as indicated in Figure 19.

In Figure 18, the paths. of movement have for convenience been illustrated as straight lines. This is not strictly true, because the two rectilinear movements are produced by cranks rotating at different speeds, so that the resultant movement would not be exactly rectilinear, but, it is quite close thereto, and on the assumptions made in the foregoing specific example the termini of the various strokes would be as illustrated in Figure 18.

To explain more explicitly, by referring to Figures 18 and 19, lines A-B, CD represent the stroke of the base frame 43 and lines A-C, B-D represent the stroke of the cylinder frame 44. Now by referring to Figure 18 and assuming that the lens is moved over the lap, by the combined action of the base and cylinder frames only and assuming that the starting position of the center of the lens surface to be ground is at a, then lines ab, b--c, c-d, d-e, etc., will represent the general path of movement of the lens. In other words, the lens will move diagonally across the lap until the center of the lens surface reaches position b on line BD at which time the base frame 45 will have reached the end of its first stroke.

Inasmuch as the cylinder frame 44 travels slower than the base frame 43, it follows that as the base frame reaches the end of its first stroke, the cylinder frame will not have quite completed its first stroke with the result that as the cylinder frame begins its second stroke, the continued movement of the cylinder frame to complete its first stroke will move the lens along the line b-c to the position c on line CD. Then, as the cylinder frame begins its second stroke, the lens will be moved along the line 0-1! to the position d on line A-C. As the lens reaches the position d, the base framewill have completed its second stroke, and as the base frame begins its third stroke, the lens-will be moved along the line d-e and will reach the position e as the cylinder frame reaches the end of its second stroke. As the cylinder frame begins its third stroke, the lens will be moved along the line e-f, etc., during the succeeding strokes of the base and cylformer lines so that the lens spindle frame upon the lens is of the lens transversely of the lap'from B to C will gradually increase in length until the lens reaches the position a when the general -direc-- tion of; the'lens will be from a to b' to c to 41', etc. I

It will thus be noted that while the lines a-b, b--c, c -d, etc., of the general path of movement of the lens over the lapare substantially parallel with corresponding lines a'-b', b'--c', cd',

etc., noneof these latter lines coincide with the will be driven back and forth across the face of the lap a multiplicity of times if actuated by'the base and cylinder frames only, before the lens will travel twice in the same path. If now the rotary action of the added to that of the base frame 43 and cylinder frame 44, 'it will be understood that while the general direction of the lens over the face of the lap is substantially line of travel the same: as illustrated in Figure 18, the actual cular or elliptical nature as illustrated in Figure 19 where the path of the lens is from a: to y to 2,

etc. The lines ,of'travel of the lens are further deviated one-from another by fact of the belt drivesjbetween drive shaft 24 and driven shafts I4, I and I6 and the well known phenomena known as belt creep, whereby'the driven pulley always rotates at a slightly slower peripheral speed than the drive pulley. Also when the circular motion of the spindle frame 45 is reversed by action of the clutch mechanism on pulleys I'I the line of travel of the lens is still further altered with the result that the operation of the lens may continuealmost indefinitely before the lens will travel twice in the same path.

If' other ratio values are desired from that taken in the illustration to distribute the grinding action of the lens upon' the lap, this may readily obtained during the "operation of the machine by shifting any one or combination of the coupling elements .34 to bring the gear teeth 36 thereof in meshing engagement with corresponding gears 98, by altering the length of the throw of either the drive blocks 59' or 12 for the base and cylinder frames or both of these throws or by anycombination of the throws and of the --coupling elements Furthermore, additional ratio values of operation may be quickly and easily obtained by rearranging the drive and 'ven pulleys 2|, '22, 23, I1, I0 and I9 for the power transmission mechanisms in the gear case I, said pulleys being madeinterchangeable for this purpose. w

It willthus be seen that I have provided a machine having a drive mechanism for the lens 1Wh1Ch, when coupled with the relatively high pressure obtained between the lens andthe grinding lap, will not only be very rapid in operation,

butwill also produce a polished surface which is free from distortion and. is scientifically accurate.

y Com ensating device In order ,to further enhance the eflicincy of my surface grinding apparatus, particularly when grinding curved-surfaces having relatively short radii, I- have provided a compensating device which co-acts with the lens holder for maintain- .ing a-uniformpressure between the-lens and lap b mechanically reversing the direction of moveof the lens will be of a more circomprises a plate I9l composed preferably of spring metal which has one end thereof rotatably mounted upon a spindle I90 mounted in a bracket I99. The ends of the plates I91 mounted on the spindle are each positioned between a pair of roller bearings 200 so that the plates are supported to freely rotate about the axis of the spindle I99: These plates I91 extend outwardly from the spindle a sufllcient distance to remain in contact with the roller I96 during the reciprocal and rotary movement thereof produced by the action of The spring plates I9l are preferably reenforced by plates I positioned adjacent the outer sides the base, cylinder and spindle frames.-

thereof and secured thereto by a clamping bolt 202 which is positioned intermediate the roller I96 and spindle I98. The clamping bolt 202 is secured to the plates I91 and "I by nuts 203 screw threaded on the bolt and positioned one at either side of each pair oi plates whereby the outer ends of said plates may be adjusted toward and from each other by screw threading the nuts upon thebolt 202 to properly position the outer ends of the plates relative to the roller I96 and than to secure said plates in the,adiusted posion. v

The bracket I99 is mounted-upon the housing I at one side of the spindle 46 by means of a square headed, shouldered stud 209- secured to the side wall of the housing and which has the head 201 provided with a knob 209 by which the lever may be manually swing for rotating the screw The outer or free ends of thecontact arms I95 are normally maintained by the bolt 202 spaced apart a distance slightly greater than the diameter of the roll I96 and the vertical movement of the bracket I99 produced by the screw 206 is for bringing one or the other of these arms into frictional engagement with the periphery of the roller I96 so that as'the spindle I46 is moved laterally duringthe grinding operation, the roller I96 will move along, the contact arm engaged therewith with a rolling motion.

, The operation of the compensating mechanism will now be understood by referring, to Figure 1'! wherein the lap I20 is constructed for grinding a 'convex surface and thespindle 46 is indicated by full lines substantially midway between fathe extreme lateral positions assumed thereby during the grinding operation and .in a plane,

stanti'ally I29. When the spindle 46 and lap 120 are thus,

related to each other, the centerof the lens will contact with the lap midway between the longitudinal' axis thereof, as illustrated by the arrow M. New considering that the spindle 46 is being moved toward the left hand side of I the. lap to midway between the ends of thfeZ-fip the position illustrated by broken lines, it will be observed that the roller I96 contacting with the upper disposed contact arm I 95 will tend to roll in a clockwise direction so as to produce a rotary movement of the spindle 46 in the same direction. This rotation of the spindle 46 in a clockwise direction will produce a corresponding rotation of the lens-holder II! in the same direction so that as the lens moves from the lower central portion of the lap along the upwardly curved portion thereof the rocking action of the work holder as hereinbefore described will be assisted by the rotation of the spindle for reducing the thrust of the lens against the curved surface of the lap with the result that the lens will engage the outer portions of the lap with the same pressure as it engages the central lower portion thereof.

Furthermore, as the spindle begins its return movement, the engagement of the contact arm with the roller I96 will immediately cause the spindle to be rotated in a counter-clockwise direction which, in turn, overcomes the inertia of the lens and tends to rock the lens holder II! in the same direction and thereby swing the lens toward the center of the lap, that is, in the direction of axial travel of spindle 46. In other words, the swinging of the lens holder II1 produced by the frictional engagement of a contact arm I95 with the roller I96 produces a corresponding swinging movement of the lens across the face of the lap and thereby overcomes the would be otherwise produced and the lap.

It will be now observed that if a concave lens is. mounted upon the lens holder as shown in Figure 15, the side thrust of the lens upon the lap would be the reverse of that when grinding a side thrust which between the lens convex lens, that is, the side thrust of the lens would be against the center of the lap and, therefore, it is necessary to effect rotation of the spindle 46 and lens holder H1 in the opposite direction to overcome the side thrust when grinding a concave lens from that when grinding a convex lens. The adjustment of the compensating device to effect proper rotation of the spindle 46 when grinding convex lenses is readily accomplished by moving the contact plates I upwardly to bring the lower contact plate into frictional engagement with the roller I96 through the medium of. the lever 201 and screw 206. As hereinbefore stated, the compensating device is used only when grinding surfaces having a complex curvature, and when grinding substantially flat surfaces or surfaces having only a slight curvature the function of the compensator is not required and the plates are readily moved to a neutral position out of engagement with the roller I96 by swinging the arm 26! to an intermediate position.

Lap adjusting means do not accurately align with the corresponding axes of the grinding lap. Therefore, in order to readily bring the axes of the lens and of the grinding lap into registration with each other, I have provided a simple mechanism associated with the lap spindle I29 for adjusting the lap to the lens holder II'I. This mechanism, see Figures 1 and 2, comprises an arm 2I6 which Is secured at one end to the lower end of the spindle I29 to extend radially therefrom. The arm 2I0 has the outer end thereof extended through an elongated vertically disposed slot 2 formed in the lower portion of the extension 3 of the housing I. The length of the slot 2 is sufficient to permit the vertical movement of the arm 2I0 therein during the movement of the spindle I29 from the operative to the inoperative positions thereof. The width of the slot 2| I is suflicient to permit a limited swinging movement of the arm about the axis of the spindle I29 whereby the lap I26 carried by said spindle may be rotated to bring the longitudinal and transverse axes thereof in alignment with the corresponding. axes of the lens carried by the lens holder III. A control plate 2I2 for the arm ZIU is secured to the housing I adjacent the slot 2| I. This control plate M2 is an L-shaped member having one leg thereof positioned in a horizontally disposed guide slot 2I3 formed in the outer face of the housing I to extend rearwardly from the slot 2. A screw member 2 is connected with this leg of the plate and extends through an elongated slot 2I3' formed in the housing at the base of the slot 2I3 into threaded engagement with a nut 2M positioned inside the housing for adjustably clamping the plate to the housing, The other leg of the plate is provided with an elongated vertically disposed slot 2I5 adapted to receive the outer end of the arm 2III therein. This slot M5 is of substantially the same length as the slot 2 but is of only about the same width as the adjacent end of the arm 2I0 so that as the plate is moved longitudinally of the housing I the arm 2H! and spindle I29 will be rotated thereby, to bring the longitudinal and transverse axes of the lap into alignment with the corresponding axes of the lens.

Automatic time control In order that the machine may be automatically stopped after a predetermined period of operation, I have provided a simple control mechanism for automatically bringing the drive shaft 21 out of operative connection with the source of power. This mechanism as illustrated in Figures 1, 3, 6 and '7, comprises a control lever 2" which, in this instance, is in the form of a rod having one end bent to form a U-shaped recess 2I'I' for receiving the belt I93 therein as shown in Figure 1. The other end 2H" of the lever 2" is bent upwardly and extends through a U-shaped bracket 2I8 with the upper end thereof secured in any suitable manner as by a set screw ,2I9 to a flanged or cup-shaped collar 220 which rests upon the upper end of bracket 2I6. The bracket 2I6 is secured to the lower portion of the housing 'I intermediate the ends thereof and rotatably supports end 2"" of lever 2". The lever 2|! is yieldingly urged in a direction to move the belt I93 from engagement with the drive pulley 26 onto the idle pulley 29 by a spring 222*coiled upon the end portion 2I'I""of the lever with one end thereof engaging the bracket 2" and the other end connected with the lever as shown in Figures 1 and 7. The lever 2" is releasably maintained in position for holding the belt upon the drive pulley 26 against the action of spring 222 by a control arm 223 which extends vertically from the collar 22! upwardly. The control arm 22! is plvotally connected with the housing I as at 226a short distance below the upper end thereof. The lower end of the arm is normally positioned wlthina recess 225 formed in the marginal flange 226' of the collar 22. when the lever 2| I is in position for maintaining the belt-in engagement-with thedrive pul ley 23.

A pair of guide pins 226 secured to the housing I, one adjacent either side of the arm 223 near the lower end thereof, co-actswith the pivot 22 for maintaining the arm against being dis- 'maintained against being moved inwardly by the action of spring 221 by. a push rod 226 loosely mounted for longitudinal sliding movement in a' pair of studs 22! secured to the cover 2 as shown in Figures 1 and 3, and a collar 23!! secured to said nod and which contacts with one of the studs 223. The inner end of the push rod 228 extends a short distance over the upper marginal edge of an. indexdisk 23f secured, as shown in Figure 3,'to the upper end of shaft 232 which extends downwardly through the cover 2 and is journaled in a bearing sleeve 233 secured to the under side of the cover 2 adjacent one side of the cam shaft l66 as shown in Figure 5. The lower end of the shaft 232 is operatively connected with the cam shaft I66 by a gear 236 and worm 235 secured respectively to said shafts.

It will beseen, therefore, that the disk 23l is rotated by the shaft I66 and said disk is provided with a plurality of, in this instance thirty, apertures 23l arranged in uniform circumferential spaced relation to each other and in concent-ric relation. with the disk for alignment with the inner end of the push rod 228. These apertures 23I may be spaced aparta distance correspond- 4 ing to the amount of travel of the disk during one minute of operation of the machine, or any multiple or'fraction of a minute as desired. A throw-out or control member 236 adapted to be received in the apertures 23l is associated with said disk for actuating the rod 228. This throwout or control member 236, in this instance, 'is a U-shaped member having .one leg 231 thereof of considerably greater length than the other leg 231 and slidably mounted in a bore 232. provided in the upper end of shaft 232. The leg 231' of themember 236 is spaced from the other leg 231 a distance corresponding to the distance the aper tures 23! are spaced from the axis of the shaft 232 andis adapted to be received in any one of the apertures 23l'. It will now be observed that the control member 236 may be brought into engagement with any one of the apertures 234 by lifting the same upwardly a short distance as illustrated by broken lines in- Figure 3 and then revolving the member about the leg 23'! as a pivot to bring the leg 231' into alignment with the desired one of said apertures. The inner end of push rod 223 is oppositely tapered to form cam surfaces 228'. These cam surfaces are normally ma ntained in the path of movement of the leg 231' of the control member 236 by the stop collar 230 and by the spring 221 acting through the medium of the arm 222.

It will now be observed that when the time control is in operation, the machine may be automatically" stopped by the engagement of the throw-outmember 236 with the push rod 228 at any multiple of one minute period of operation throughout thirty minutes by inserting the end 231' in one of the apertures 30' positioned rear wardly in the direction of travel of the disk from operating means tained in operation. At the end of the selected time period the engagement of the end 231' with the inner end of the push rod 223 will effect sufficient outward longitudinal movement of said rod to bring the lower end of the control arm 223 out of registration with the slot 225 thereby releasing the collar-220 and permitting the spring 222 to rock-the lever 2l1 outwardly suflieiently to bring the belt from engagement with the drive pulleys 23 into operative engagement with the idle pulley 29. The outward swinging movement of the lever 211 is limited by a stop screw 2" screw threaded in the housing I and adapted to engage a boss 2 provided on the collar 220 as shown in Figure 7. A

In order that the belt. I93 may be manually moved from the idle pulley 23 into operative engagement with the vvdrive pulley 28, I have provided a control lever 242 which has one end thereof secured in the boss 2 and which extends forwardly. from the collar 220 to a convenient position adjacent the forward end of the housing l as shown in Figure 1.

Although I have shown and particularly described the preferred embodiment of my invention, I do not wish to be limitedto the exact construction shown as various changesboth in the form and relation of the parts thereof may readily be made without departing from the spirit of the invention as set forth in the appended claims.

I claim: 1

1. In a surface grinding machine of the class having a grinding lap and a work holder mounted in co-operative relation therewith, in combination, operating means producingrelative movement of thegrinding lap and work holder to move the work carried by the work holder with compounded reciprocative and circular motions in continuously changing paths across the face of the lap, said operating means including a clutch element, and means for actuating said clutch element to automatically reverse the direction of the circular motion at frequent intervals. I

2. In a' surface grinding machine of the class having a grinding lap and a work holder mounted in co-operative relation therewith, in combination, operating mechanism connected with one of said members for producing compounded reciprocative and 'circular motions thereof relative to the other member by the work holder will be moved across the face of the lap in continuously changing paths,

said operating means including two drive. members associated with the circular motion, a clutch element mounted between said drive members, and means actuated by the operating mechanism for producing relative movement of the clutch element and said drive members to connect the clutch element alternately with the drive members whereby the direction of the circular motion is reverse at frequent intervals.

3. In a surface grinding machine, a grinding element, a work holder element mounted in cooperative relation therewith, operating means for producing movement of a piece of work carried by the work holder element across the face of the grinding eement in continuous changing paths including a plurality of carrier members having movement relative to each other and connected with at least one of said elements, means rotatably supporting one of the carrier members,

whereby the work carried for rotating said latter carrier member, and control means associated with said latter operating means for automatically reversing the direction of rotation of the rotatable carrier element at predetermined intervals.

4. In a surface grinding machine having a grinding element and a work holder element mounted in cooperative relation therewith, in combination, a case for supporting said elements, power operating means mounted in said case and connected with at least one of said elements to move the work carried by the work holder element across the face of the grinding element in continuous changing paths, and control means associated with the power operating means including a shaft rotatably mounted in said case and operatively connected with the operating means to be rotated thereby, an index disc operatively connected with said shaft and positioned exteriorily of the case, said disc having a plurality of apertures arranged in predetermined spaced relation with each other, a manually operable control member movable into engagement with any selected one of said apertures to be moved in unison with the disc, and a power switching means connected with said case andarranged in cooperative predetermined relation with the disc to be actuated by said control member for automatically discontinuing the operation of the machine after a predetermined period of operation thereof.

5. In a surface grinding machine, a grinding element, a work holder mounted in cooperative relation therewith, means including a control lever for producing relative movement of the grinding element and work holder toward each other to bring the work carried by said holder into engagement with the grinding element, pressure means set into operation by continued movement of said lever after the work and grinding element are in engagement with each other for produc-' ing pressure between said work and element, and pressure indicating means operatively connected with said lever and said pressure means, said pressure indicating means being of such a character that the same is rendered active by the cooperation of the lever and said pressure means only after the work contacts with the grinding element for indicating the pressure engagement of the work with said element.

6. In a surface grinding machine having a grinding element and a work holder mounted in cooperative relation therewith, in combination, means including a control lever for producing relative movement of the grinding element and the work holder toward each other to bring the work carried by said holder into engagement with the element, means including a springset into operation by movement of said lever only after the work and element are in engagement with each other for producing a predetermined pressure between the work and element, and means including a dial and a pointer coacting with the lever and spring for indicating the amount of said pressure.

7. In a surface grinding machine having a grinding element and a work holder element mounted in cooperative relation therewith, in combination, means including a control lever for producing relative movement of the grinding element and work holder element toward each other to bring the work carried by said holder into engagement with the grinding element, means including a spring set into operation by movement of said lever only after the work and element are in engagement with each other for producing a predetermined pressure between the work arid element, and pressure indicating means cooperating with the latter means including a dial member resiliently connected with the lever by said spring so as to move with said lever prior to the engagement of the work with the grinding ele-' ment, and a pointer actuated by said lever with respect to said dial subsequent to the contact of the work with the grinding element for indicating the amount of said pressure.

8. In a surface grinding machine, a grinding element, a work holder mounted in cooperative relation therewith, means including a control-lever for producing relative movement of the grinding element and work holder toward each other to bring the work carried by said holder into engagement with the element, means including a rock member set into operation by said lever only after the work and grinding element are in engagement with each other for producing a predetermined pressure between said work and element, and

means co-acting with said rock member for intermittently decreasing the pressure between the work and grinding element during the operation of the machine.

9. In a surface grinding machine, a grinding element, a work holder mounted in cooperative relation therewith, means including a manually operated control member for producing relative movement of the grinding element and work holder toward each other to bring the work carried by said holder into engagement with said element, means including a cam member brought into operation 'by continued movement of the control member after the work and grinding element are in engagement with each other for producing a chine having a grinding element provided with a curved grinding surface, a work holding means including a spindle mounted to rock about an axis extending transversely of said grinding surface in a plane at one side thereof, operating means associated with said work holding means for pro ducing reciprocative movement of the spindle to move the work carried by the work holding means back and forth across said grinding surface in pressure engagement therewith, and a compensating means including a relatively fixed element having operative engagement with the spindle and rendered effective by said reciprocative movement of the spindle for rocking said spindle and the 1 work holding means in a direction to move the work carried thereby about said axis in the direction of movement of said work produced by the reciprocative movement with respect to the grinding surface.

11. In a surface grinding and polishing machine having a grinding element provided with a curved grinding surface, a work holding means including a spindle mounted to rock about an axis extending transversely of said grinding surface in a.

plane at one side thereof, operating means associated with said work holding means for producing reciprocative movement of the spindle to move the work carried by the work holding means back and forth across saidgrinding surface in pressure engagement therewith, and compensating means including a contact arm mounted in substantially a fixed position adjacent said spindle and frictionally associated with said spindle adapted tocooperate with the reciprocative movement for producing a rocking movement of said spindle and the work holding means in a direction to move the work connected therewith about said axis in the direction of movement of said work produced by the reciprocative movement with respect to the grinding surface.

12. In a surface grinding and polishing machine having a grinding element provided with a curved grinding surface, a work holding means including a spindle mounted to rock about an axis extending transversely of said grinding surface in a plane at one side thereof, operating means associated with said work holding means for producing reciprocative movement of the spindle to move the work carried by the work holding means back and forth across said grinding surface in pressure engagement therewith, and. compensating means including two resilient arms arranged one at either side of said spindle adapted to be frictionally associated with said spindle during the reciprocative movementfthereof for producing rocking movement of the spindle in directions to move the work about said axis in the direction of movement of the work produced by the reciprocative movement with respect to the grinding surface, and manually operated means for selectively moving the arms into relation with the spindle depending upon whether the grinding surface is of concave or convex cu vature.

13. In a machine for grinding lenses wherein a grinding element provided with a curved grinding surface and a work-holder element are mounted operating means for producing relative reciprocating movement of the elements including a supporting member rotatably mounted to rock about an axis disposed transversely across said surface of the grinding element, means connecting one of the elements with said supporting member including a second supporting member arranged at one side of the axis of the first supporting member, and means pivotally connecting said second member to the first member whereby said one of the elements will be mechanically rocked forwardly by the frictionalresistance produced between the lens and grinding element during said reciprocative movement about said axis in the direction'of the reciprocating movement, said later means including relative adjusted members whereby the surface of the element carried thereby may be moved from a position at one side of the axis of rotation of the first member to a position at the opposite side of said axis so that a convex or concave lens maybe ground in the manner set forth.

14. In a machine for grinding lenses, in combination, a grinding lap having a base axis anda cylinder axis arranged substantially normal to each other, a supporting member mounted to rotate about an axis extended substantially normal to one of said axes of thelap, operating means forreciprocating the supporting member longitudinally and laterally of said'axis of rotation,

a worksholder pivotally connected with the supand out of cooperative site side thereoffor the purpose set forth.

supporting member, means releas--' pensating means operatively connected with the supporting member and rendered effective by one of said reciprocative movements of the supporting members for alternating effecting rotation of said member in reverse direction.

15. In a machine for grinding lenses, in combination, a lap having a curved grinding surface provided with a base axis and a cylinder axis disposed in right-angular relation to each other, a supporting member mounted to rotate about an axis arranged substantially normal to one of said axes of said grinding surface, operating means for reciprocating the supporting member longitudinally and laterally of said axis of'rotation, a work-holder pivotally connected with the supporting member to rock about an axis substantially parallel with the second one of said axesof the grinding surface, said work-holder having a work-holding element positioned in a plane over the grinding lap in spaced relation to said axis of rotation of the supporting member, and means releasably securing the work to said portion of the work-holder, said work-holder including members adjustable relative to each other whereby the work may be moved from a position with the surface thereof to be ground located intermediate bination, a grinding lap having a base axis and a cylinder axis disposed in right-angular relation to each other, a supporting member mounted to rotate about an axis extending substantially normal of one of said axes of the lap, operating means for reciprocating the supporting member longitudinally and laterally of said axis of rotation, a work-holder comprising an inverted substantially U-shaped frame, means connected with the supporting member at opposite sides of said axis of rotation thereof and pivotally engaging the side members of the work-holder frame for rotatably supporting the frame with the transverse portion' thereof'located in a plane over the grinding lap and in outwardly spaced relation to said axis of rotation, and means securing the work to said transverse portion of the frame, said workholder frame being provided with means for adjustably securing the transverse portion thereof to the side portions whereby'the Work-holder may be moved from a position with thesurface of the work to be ground located at one side of the axis of rotation of the supporting member to the oppo- 17. In a surface grinding machine, a grinding lap, a work-holder mounted in co-operative relation. therewith, means including a manually operated control element for producing relative movement of the grinding lap and work-holder toward each other to bring the work carried by said holder into engagement with the lap, said means also including a spring set into operation by movement of said control element only after the work and lap are in' engagement with each other for producing a predetermined pressure between the .work and lap, and a dial member mounted in co-operative 'relationwith the control element, and connected with said spring so that the dial member will move in unison with the control element prior to the engagement of the workwith the grinding lap and will remain stationary during continued movement of the control element following said engagement of the work and lap, whereby the amount of pressure between the work and the lap may be readily determined by the co-action of said element and dial.

113. In a surface grinding machine, a grinding lap, a work-holder mounted in co-operative relation therewith, means for moving the lap toward and from the work-holder to bring the work carried by said holder into pressure engagement with said lap, said means including an oscillating arm operatively connected with the lap, a manually operated lever, means including a spring yieldingly connecting the lever with said am. and a dial member connected with the arm to move therewith and arranged in co-operative relation with the lever for indicating the amount of pressure between the .work and the grinding lap.

19. A grinding machine as in claim 18 having means connected with said lever for intermittently changing the degree of pressure between the work and the lap. 10

WILLIAM A. LDCHIART. 

